1. Field of the Invention
The invention relates to turning machines, with or without a numerical program control facility, of the kind comprising two indexing turrets and a co-operating chuck for holding the workpiece.
2. Description of the Prior Art
In a configuration known as a three axis machine tool, the upper turret is movable along the main machine axis and also perpendicular to the main machine axis and the lower turret is capable of movement along the main machine axis only. In the configuration, however, described in U.S. Pat. application Ser. No. 582,263, filed on May 30, 1975, and designated a four axis machine tool, the lower turret is capable also of movement perpendicular to the main machine axis.
In such machines it is often desired to machine a workpiece between centres. This is normally achieved by mounting a centre support in a tooling station on one of the turrets. This procedure, however, is not very satisfactory since such a centre support has only a light duty and is not suitable for supporting heavy components. Moreover, this arrangement is not capable of sustaining the heavy cutting forces involved in machining to the full capacity of the machine.